This application claims the priority of European Patent Application No. 00810705.4-2302 filed Aug. 7, 2000, the disclosure of which is incorporated herein by reference.
The invention relates to an apparatus for automatically trimming the open side edges of bound printed products, such as books or brochures. Such an apparatus includes a trimming station which has a trimming device with at least one blade that can be driven in a plane extending perpendicular to the extension of the printed products. A positioning device is provided with which a respective side edge of the printed products can be positioned for a cut on a trimming table. A pressing device presses the positioned printed products over essentially the entire format for the cut.
An apparatus of this type is commercially available under the name xe2x80x9cMerit Sxe2x80x9d by Mxc3xcller-Martini AG. The apparatus is a so-called three-side trimmer that has a blade for the front cut, the blade being disposed in a trimming station and oriented transversely to the transport direction, and two blades for making the top and bottom cuts which are spaced from one another and oriented in the transport direction. Conveyor belts transport the untrimmed printed products to the trimming station, where they are precisely aligned. A pressing plunger presses the positioned printed products. The pressing pressure is pneumatlly adjusted. Trimming is effected against plastic trimming tabs.
For assuring a high trimming quality, even in books having a thickness of, for example, 4 cm, in the xe2x80x9cMerit Sxe2x80x9d the pressing plunger presses the printed products essentially over the entire format. The pressing plunger is therefore format-specific. If a for changes, a new pressing plunger must be mounted. This device is therefore only suitable for mass production. For producing short runs or individual products with continuously-changing formats, the pressing plungers would have to be exchanged for each format change, and the trimming mechanisms would have to be adjusted to the format. It is therefore not economical to produce short runs or individual products with this device.
EP 0 842 746 A discloses a device for trimming the open side edges of bound printed products, in which two respective printed products to be processed are positioned on a rotatable clamping device. The open side edges are t ed consecutively with one blade; the printed products are rotated after a cut. In this case, the printed products are only pressed in a comparatively small region. Also in this device, if the entire format is supposed to be pressed, the pressing plunger must be exchanged when the format changes.
It is an object of the invention to produce a device of the aforementioned type that assures a high trimming quality in the trimming of books and brochures, and is also suitable for short runs and individual products.
The above and other objects are accomplished in accordance with the invention by the provision of an apparatus for automatically trimming the open side edges of bound printed products as first described above, wherein two further trimming stations and a transport device are provided for transporting a respective printed product from the first trimming station to the second trimming station, and from the second trimming station to the third trimming station, and each of the three open side edges of the printed products is trimmed with a stationary blade in each trimming station.
According to a further aspect of the invention there is provided a method for implementing the apparatus of the invention.
In the apparatus and method of the invention, the three-sided trimming of a book occurs not in a single trimming station, but sequentially in a plurality of consecutive, staggered trimming stations. The pressing device of each trimming station, and particularly the pressing plunger, can be tailored to a maximum format. In printed products having a smaller format, the pressing plunger can harmlessly protrude beyond the printed product at the sides that are not to be trimmed in the respective trimming station. Thus, all printed products having the maximum format or a smaller format can be pressed and trimmed without necessitating the exchange of the pressing plungers. It is thus not necessary to exchange the pressing plunger when the format is changed. Because each trimming station only requires a single blade, these massive blades can always maintain a fixed position. No complicated adjustment procedure is needed.
It is possible to process an arbitrary sequence of book sizes consecutively, economically and with a high output, when, in accordance with a modification of the invention, adjustable stops are provided in the individual trimming stations for positioning and aligning the printed products to be trimmed. This adjustment can be made from cycle to cycle, so an arbitrary sequence of book sizes can be processed consecutively and simply. In accordance with a modification of the invention, spring-loaded pressing plungers accommodate a change in the book thickness. If the book thickness changes, therefore, the pressing plungers need not be adjusted to the thickness of the printed products.
A further advantage of the device according to the invention is that the order of the cuts can be arbitrarily selected and therefore customized for the printed products. The top, bottom and front cuts can therefore be made in a random order. The trimming stations can be arranged consecutively in a line. Other arrangements are also possible, however. In particular, the trimming stations can be arranged such that for example, printed products having the smallest format or printed products having the largest format can be guided through the trimming stations in a straight line. The corresponding printed products, for example those having the smallest format, may then be subjected to only minimal lateral adjustments in the individual stations. The arrangement of the individual stations can therefore be tailored to the user""s needs. The trimming stations can be offset from one another, for example, or arranged such that the printed products are guided through the trimming stations at an angle with respect to the spine. One of the corners of the printed products is then respectively aligned at stops.